Methods Of Affecting Material Properties And Applications Therefor

ABSTRACT

Methods of affecting a material&#39;s properties through the implantation of ions, such as by using a plasma processing apparatus with a plasma sheath modifier. In this way, properties such as resistance to chemicals, adhesiveness, hydrophobicity, and hydrophilicity, may be affected. These methods can be applied to a variety of technologies. In some cases, ion implantation is used in the manufacture of printer heads to reduce clogging by increasing the materials hydrophobicity. In other embodiments, MEMS and NEMS devices are produced using ion implantation to change the properties of fluid channels and other structures. In addition, ion implantation can be used to affect a material&#39;s resistance to chemicals, such as acids.

This application is a divisional of U.S. patent application Ser. No.13/470,731 filed May 14, 2012, which claims priority of U.S. ProvisionalPatent Application Ser. No. 61/486,296, 61/486,297 and 61/486,299, allfiled May 15, 2011, the disclosures of which are all incorporated byreference in their entireties.

FIELD

This invention relates to ion implantation and, more particularly, toion implantation for precision material modification.

BACKGROUND

Ion implantation is a standard technique for introducing material into aworkpiece. A desired implant material is ionized in an ion source, theions are accelerated to form an ion beam of prescribed energy, and theion beam is directed at the surface of the workpiece. The energetic ionsin the beam penetrate into the bulk of the workpiece material and affectboth the surface and depth of the workpiece material under certainconditions.

While ion implantation is typically used to alter the electricalproperties of a workpiece, it can also be used to affect other materialproperties, such as resistance to specific chemicals, adhesion,hydrophobicity, hydrophilicity, and others.

Inkjet printing is a technique that ejects liquid ink onto paper. Theinkjet print head (or cartridge) has nozzles that are about the size ofa needlepoint through which the ink is ejected. FIG. 1 is a view of anembodiment of an inkjet printer head 1. In some embodiments, such asthat shown in FIG. 1, the head 1 may include multiple nozzles 2 toaccommodate a plurality of colored inks 3. The printing process mayinvolve a nucleation step using the ink, bubble growth, ejection of anink drop, and refilling of the inkjet head.

Printing resolution and lifetime are both limited by the inkjet aperturesize. Smaller apertures can provide higher resolution, but the lifetimeis reduced due to clogging of the aperture with the ink. Applying inkjetprinting to new fields such as, for example, biochips, metal wiring,liquid crystal displays (LCDs), organic light-emitting diodes (OLEDs),or MEMS devices is being investigated. However, suitable printing headsare required for each application before widespread adoption can occur.For example, ejection of high viscosity ink droplets may need to providehigh precision, high frequency, no chemical reaction, and no clogging.Thus, it may be beneficial to affect the properties of the material usedto create the print head to minimize the interaction between the ink andthe print head.

Another application where affecting material properties may bebeneficial is MEMS and NEMS devices. MEMS devices relate to smallmechanical devices driven by electricity. NEMS devices relate to devicesintegrating electrical and mechanical functionality on the nanoscale.Examples of these devices are accelerometers and gyroscopes, thoughthere are countless others. MEMS and NEMS processing is extremelycomplex. One difficulty is that precise material modification to locallyaffect material properties has not been effectively demonstrated.

In addition, many materials would benefit from increased or modifiedchemical resistance. High energy ion implantation has been used in thepast to affect chemical resistance of some materials. High energyimplants may be time-consuming and may lead to increased manufacturingcosts. These high energy implants also typically used exotic speciessuch as Al, Mg, or Ti, which may be expensive. Furthermore, previousmethods only treated a thick layer on the surface of the material and insome instances hardened the surface, which affected flexibility of thematerial.

Therefore, in each of these examples, it would be beneficial to have animproved method of precisely affecting material properties. Such animproved method could then be applied to various technologies, includinginkjet printing, biochips and MEMS and NEMS devices, such asaccelerometers, pressure sensors and gyroscopes.

SUMMARY

Methods of affecting a material's properties through the implantation ofions, such as by using a plasma processing apparatus with a plasmasheath modifier. In this way, properties such as resistance tochemicals, adhesion, hydrophobicity and hydrophilicity, may be affected.These methods can be applied to a variety of technologies. In somecases, ion implantation is used in the manufacture of printer heads toreduce clogging by increasing the material's hydrophobicity. In otherembodiments, MEMS and NEMS devices are produced using ion implantationto change the properties of fluid channels and other structures. Inaddition, ion implantation can be used to affect a material's resistanceto chemicals, such as acids.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present disclosure, reference is madeto the accompanying drawings, which are incorporated herein by referenceand in which:

FIG. 1 is a view of an embodiment of an inkjet printer;

FIG. 2 is a block diagram of a plasma processing apparatus having aplasma sheath modifier;

FIG. 3 illustrates hydrophobic modulation;

FIG. 4 is a cross-sectional side view of an embodiment of a print head;

FIG. 5 is a cross-sectional side view of sidewall porous materialformation;

FIG. 6 is a cross-sectional side view of a workpiece being implanted;

FIGS. 7A-B represents an embodiment of helium implantation into astructure;

FIGS. 8A-C show the results of implantation according to FIG. 7;

FIGS. 9A-D show a representative sequence to treat an inkjet print head;

FIG. 10 represents a typical biochip;

FIG. 11 represents a micropump;

FIG. 12 is an exploded view of the internals of an accelerometer; and

FIG. 13 is a cross-sectional side view of one embodiment of a 3Dstructure or feature being implanted.

DETAILED DESCRIPTION

The embodiments are described herein in connection with specificmaterials and devices, but these embodiments should not be limitedmerely to the materials and devices listed. For example, some of theembodiments are described herein in connection with MEMS and NEMS, butthese embodiments also may be used with other devices. Similarly, someof the embodiments are described herein in connection with printers suchas inkjet printers, but these embodiments also may be used with otherprinting devices. These inkjet printers or other printing devices can beused for paper or other applications known to a person skilled in theart. While a specific type of implanter is disclosed, other ionimplantation systems known to those skilled in the art that can focus anion beam or that can implant particular regions of a workpiece with orwithout a mask on, above, or a distance from the workpiece also may beused in the embodiments described herein. While the term “hydrophobic”is used, throughout, it may be advantageous to render a surfacehydrophilic instead. Thus, the invention is not limited to the specificembodiments described below.

While a beamline or plasma doping tool may be used to implant ions toaffect a material's properties, a plasma processing apparatus having aplasma sheath modifier may be used. This has an advantage that selectiveimplantation of 2D or 3D surfaces may be performed without usingphotoresist, other hard masks, or proximity masks. This sort ofpatterned implant reduces processing time and manufacturing costs.Scanning the workpiece or device to be implanted may be combined withbiasing such a workpiece or device or changing the plasma parameters toaccomplish this selective implantation.

FIG. 2 is a block diagram of a plasma processing apparatus having aplasma sheath modifier. The plasma 140 is generated as is known in theart. This plasma 140 is generally a quasi-neutral collection of ions andelectrons. The ions typically have a positive charge while the electronshave a negative charge. The plasma 140 may have an electric field of,for example, approximately 0 V/cm in the bulk of the plasma 140. In asystem containing the plasma 140, ions 102 from the plasma 140 areattracted toward a workpiece 100. These ions 102 may be attracted withsufficient energy to be implanted into the workpiece 100. The plasma 140is bounded by a region proximate the workpiece 100 referred to as aplasma sheath 242. The plasma sheath 242 is a region that has fewerelectrons than the plasma 140. Hence, the differences between thenegative and positive charges cause a sheath potential in the plasmasheath 242. The light emission from this plasma sheath 242 is lessintense than the plasma 140 because fewer electrons are present and,hence, few excitation-relaxation collisions occur. Thus, the plasmasheath 242 is sometimes referred to as “dark space.”

The plasma sheath modifier 101 is configured to modify an electric fieldwithin the plasma sheath 242 to control a shape of a boundary 241between the plasma 140 and the plasma sheath 242. Accordingly, ions 102that are attracted from the plasma 140 across the plasma sheath 242 maystrike the workpiece 100 at a large range of incident angles. Thisplasma sheath modifier 101 may be referred to as, for example, afocusing plate or sheath engineering plate.

In the embodiment of FIG. 2, the plasma sheath modifier 101 includes apair of panels 212 and 214 defining an aperture there between having ahorizontal spacing (G). The panels 212 and 214 may be an insulator,semiconductor, or conductor. In other embodiments, the plasma sheathmodifier 101 may include only one panel or more than two panels. Thepanels 212 and 214 may be a pair of sheets having a thin, flat shape. Inother embodiments, the panels 212 and 214 may be other shapes such astube-shaped, wedge-shaped, and/or have a beveled edge proximate theaperture. The panels 212 and 214 also may be positioned a verticalspacing (Z) above the plane 151 defined by the front surface of theworkpiece 100. In one embodiment, the vertical spacing (Z) may be about1.0 to 10.0 mm.

Ions 102 may be attracted from the plasma 140 across the plasma sheath242 by different mechanisms. In one instance, the workpiece 100 isbiased to attract ions 102 from the plasma 140 across the plasma sheath242. In another instance, a plasma source that generates the plasma 140and walls surrounding the plasma 140 are biased positively and theworkpiece 100 may be grounded. The biasing may be pulsed in oneparticular embodiment. In yet another instance, electric or magneticfields are used to attract ions 102 from the plasma 140 toward theworkpiece 100.

Advantageously, the plasma sheath modifier 101 modifies the electricfield within the plasma sheath 242 to control a shape of the boundary241 between the plasma 140 and the plasma sheath 242. The boundary 241between the plasma 140 and the plasma sheath 242 may have a convex shaperelative to the plane 151 in one instance. When the workpiece 100 isbiased, for example, the ions 102 are attracted across the plasma sheath242 through the aperture between the panels 212 and 214 at a large rangeof incident angles. For instance, ions 102 following trajectory path 271may strike the workpiece 100 at an angle of +θ° relative to the plane151. Ions 102 following trajectory path 270 may strike the workpiece 100at about an angle of 0° relative to the same plane 151. Ions 102following trajectory path 269 may strike the workpiece 100 an angle of−θ° relative to the plane 151. Accordingly, the range of incident anglesmay be between +θ° and −θ° centered about 0°. In addition, some iontrajectories paths such as paths 269 and 271 may cross each other.Depending on a number of factors including, but not limited to, thehorizontal spacing (G) between the panels 212 and 214, the verticalspacing (Z) of the panels 212 and 214 above the plane 151, thedielectric constant of the panels 212 and 214, or other processparameters of the plasma 140, the range of incident angles (θ) may bebetween +60° and −60° centered about 0°.

The plasma processing apparatus of FIG. 2 can be used to affect theproperties of a material. This technique can then be applied to varioustechnologies, as described in more detail below.

In one embodiment, use of multi-angle ion implantation can modify theproperty of a nozzle, channel, and inkjet printer head. These may befabricated of, for example, silicon, polymers, semiconductors,poly(dimethylsiloxane) (PDMS), SU8 photoresist or conductors. FIG. 3illustrates hydrophobic modulation can be caused by ion implantation.The hydrophobicity of a surface was modulated after implants of NF₃ andCF₄ using a plasma doping tool. A reference material, shown in thecenter of FIG. 3, has an initial contact angle of 41.58°. Theaccompanying illustration 22 depicts the shape of a droplet on thematerial. By implanting the material with NF₃, the contact angle wasreduced to 15.08°, indicating that the material has become morehydrophilic. As shown in the upper illustration 21, the droplet is morespread across the surface of the material. Conversely, the bottomillustration 23 shows the effect of a CF₄ implant. In this case, thecontact angle increases to 103.07°, indicating a high degree ofhydrophobicity. Using a multi-angle ion implant can enable changing thehydrophobic or porosity properties of either a 2D or 3D surface. Thiswill allow the correct inkjet droplet properties for a particularprinting application.

As shown in FIG. 3, ion implant can change a surface to be hydrophobicor hydrophilic. Thus, the adhesion of the ink droplets to the surfacecan be changed. The chemical compatibility or chemical resistance of thesurface also can be altered by physical changes to the implanted surfacecaused by ion implantation. Finally, different liquids may becomesuitable as inks using inkjet printing (polymers, special inks, metals,oils, nanoparticles, or others) by affecting adhesion or chemicalcompatibility. Besides enabling new printing applications, all this maylead to higher inkjet printer nozzle lifetimes.

FIG. 4 is a cross-sectional side view of an embodiment of a print head.Other designs known to those skilled in the art are possible. In oneinstance, the print head 300 is fabricated from a silicon workpiecethrough processes such as etching. The silicon devices or parts producedare then bonded to a cover 304 using an adhesion layer. This cover 304may be metal, glass, SiO₂, Si, PDMS, or SU8. In another instance, theprint head 300 is made of plastic.

The print head 300 has multiple surfaces. It has a channel 301 thatleads to the nozzle 302. It also has an exit area 303, where the nozzle302 meets the external environment. All or some of the surfaces of thechannel 301, the nozzle 302 and the exit area 303 may be implanted.These surfaces may be implanted with, for example, C, N, H, F, He, Ar,B, As, P, Ge, Ga, Si, Zn, Al, other noble gases, other p-type or n-typedopants, or other atomic or molecular species known to those skilled inthe art. The implant depth may be less than 100 nm or, moreparticularly, between approximately 1 nm and 30 nm, with a surface peakor retrograde profile to modulate the surface energy.

In one instance, the entirety of the surfaces that contact the ink inthe print head 300 is implanted. With a blanket implant, a multi-angleimplant can enable implantation of a 3D structure. The nozzle 302 andthe sidewalls and bottom of channel 301 may be implanted. The lowersurface of the glass cover 304 also may be implanted. This enablesliquid to flow without adhering or sticking to the bottom, sides, or topof the channel 301 or nozzle 302.

In another instance, only a portion of the surfaces that contact the inkin the print head 300 is implanted. This portion may coincide with areaswhere clogging is common, where ink transport is desired, or otherareas. In one particular embodiment, any corners of the print head 300are implanted to prevent ink from being retained. The corners also maybe implanted with a higher dose than other regions of the print head300.

Implanting the area where adhesion occurs between, for example, siliconand glass parts of the print head 300 may affect bonding between thesetwo parts. Photoresist or selective implants may prevent this fromoccurring. In another instance, a selective implant is performed torender certain surfaces hydrophobic while a second selective implant isused to improve or enable the bonding step between the variousworkpieces.

The implant will reduce or prevent adhesion by the ink to the print head300. The ion species that is implanted may in part affect thehydrophobicity, as shown in FIG. 3. Certain energy levels or dosesduring implantation may modify the lattice structure of the surfaces ofthe print head 300 in FIG. 4, which also may in part affect thehydrophobicity. Other mechanisms due to implant that affect thehydrophobicity may be possible. Since these regions are implanted, theywill remain hydrophobic even if cleaned because these implanted regionsare an integral part of the surface of the print head 300 instead of acoating on the surface of the print head 300 that may be eroded orwashed off. To maintain the hydrophobic state, at least a few monolayersof the surface are implanted. Uniformity of the dose and depth implantedregions may be controlled. If certain areas of the surface are implantedin a non-uniform manner or are not implanted at all, this may affectadhesion of the ink. In one embodiment, CF₄ is implanted at energiesbetween 0.5 and 6.0 kV. In a further embodiment, the voltage isdecreased over time to improve adhesion and provide interface mixingbetween the starting material and the new layer being created. In someembodiments, this material is implanted. In other embodiments, thematerial may be implanted and deposited.

In some instances, the inkjet printer head may need to be implanted toaffect different regions in opposite ways. For example, referring toFIG. 9D, the ink is stored in an ink chamber 351. The path from the inkchamber 351 to the external environment passes through a nozzle 352, andultimately through an exit area 353. Two important aspects of an inkjetprint head 350 are the ability for the ink droplets to travel throughthe ink chamber 351 and nozzle 352 with minimal impedance, and theability of the ink to not adhere to the exit area 353, thus causingunwanted stains on paper and a clogged nozzle. These requirements demandthat the interior of the nozzle 352 has the highest ink wettability andthe outside surface near the exit area 353 has the lowest inkwettability. Current practices often rely on materials selectioncombined with CVD/PVD processes to deposit a wetting and/or anti-wettinglayers on these surfaces. These types of surface treatment often havepoor adhesion between surface deposition and the substrate, and can bedifficult to apply to the small nozzle features without clogging theorifice. According to one embodiment, ion implantation technology isutilized, which produces high-strength interfaces with long service lifetime. Ion implantation can be precisely controlled, making it possibleto fine tune wettability on different parts of the inkjet print head350. In addition, ion implantation can be used to process features innanometer scales with excellent uniformity and is compatible with theexisting microelectronics manufacturing processes. Ion implantation alsoenable longer lifetime of the inkjet print head 350.

In operation, the print heat 350 is formed from a processed workpiece354 and a cover 358. The cover 358 may be glass or some other materialand is applied to the workpiece 354 after processing. Referring to FIG.9A, the workpiece 354 may be of any suitable material, includingsilicon. The workpiece 354 may be etched to form the nozzle 352, asshown in FIG. 9B. The nozzle 352 may be formed so as to be wider at thetop surface 356 than at the exit area 353, which is defined as the areawhere the nozzle 352 meets the bottom surface. Often the dimension ofthe nozzle 352 is limited by the tendency of the ink to clog. Afteretching, it may be desirable to make the nozzle 352 hydrophobic. Thus,as shown in FIG. 9C, a focused ion implant 355 using the plasmaprocessing apparatus of FIG. 2, for example, may be used to make thisnozzle area 352 hydrophobic. As described earlier, an implant of CF₄ maybe used. In some embodiments, the exit area 353 is made to have adifferent level of hydrophobicity than the rest of the nozzle 352. Insome embodiments, the hydrophobicity may be varied by controlling theimplant angle of the ions. This may also be done by performing anotherion implant from the top surface 356, or may be done via an ion implantfrom the bottom surface. Furthermore, in some embodiments, the rest ofthe top surface 356 may be treated to change the hydrophobicity of thetop surface 356. For example, the rest of the top surface 356 may beless hydrophobic than the nozzle 352. After the implantation isperformed, the print head 350 can be assembled by attaching the cover358 to the workpiece 354, as shown in FIG. 9D.

The implanted region may densify the material of which the surface iscomposed. This densification is due to the material added to the latticeof the surface during implantation. The densification may affecthydrophobic or hydrophilic properties of the surface. For example in thecase of polymer based MEMS/inkjet heads, such as PDMS and SU8, theimplantation may break some of the bonds of the polymer and create agraphitic skin layer, which is denser than the original polymer. Thiscan be done using inert gas or active species, such as carbon-basedspecies.

Another application that would beneficial from affecting materialproperties is electromechanical devices, such as MEMS and NEMS devices.These devices use polymers of various designs and for various purposes.These polymers include, for example, SU8 photoresist, PDMS, polymethylmethacrylate (PMMA), or others known to those skilled in the art. All orpart of the polymers may be frozen (i.e. the shape of the feature willnot change after implantation) or hardened using ions. For example, inthe case of implantation of resist, a conformal implant can freeze theresist such that it is capable of going through two litho processes fordual patterning lithography. In one instance, only part of a 2D or 3Dpolymer structure in a MEMS or NEMS device is implanted. For example, ina micro-valve, the fluid channel can be hardened or rendered moreresistant to a liquid though implantation. The micro-valve membrane maybe implanted with a different species or not implanted at all such thatit does not get jammed. Thus, localized implantation and control oflocalized implantation is important both due to the scale of the devicesand the different functions of these devices. This polymer hardening orfreezing may involve implantation of inert species such as a noble gasor an active species such as Si, NF₃, C_(x)H_(y), C_(x)F_(y), SiF₄,SiH₄, disilane or CF₄. Of course, other species can be implanted.

MEMS and NEMS devices also may need sidewall smoothing. Masking steps orother processing steps may cause a large amount of roughness. Smoothingthe sidewalls of, for example, a polymer can improve MEMS or NEMS deviceperformance. A noble gas may be implanted to a depth between 1 nm and100 nm, for example, and cause physical changes to the sidewall surface.Similar to polymer freezing or hardening, localized implantation andcontrol of localized implantation is important both due to the scale ofthe devices and the different functions of these devices.

Metal films in the MEMS or NEMS device can be implanted to modulate thestress. These metal films may be extremely small. Patterned or selectiveimplantation of these metal films can be accomplished without implantingneighboring or adjacent areas of the MEMS or NEMS device.

Localized processing of a MEMS or NEMS device can affect physicalproperties. For example, as described above for print heads, thehydrophobicity or porosity can be adjusted in all or part of a NEMS orMEMS device using ion implantation on either a 2D or 3D surface. Thesurfaces may be implanted with, for example, C, N, H, F, He, Ar, B, As,P, Ge, Ga, Si, Zn, Al, other noble gases, other p-type or n-typedopants, or other species known to those skilled in the art. These maybe atomic or molecular ions that contain, for example, the ionspreviously listed or other species known to those skilled in the art.

In one instance, the entirety of a surface is implanted. In anotherinstance, only a portion of a surface is implanted. For example, in abiochip or microfluidics device, a channel or region where a fluid willflow or collect can be implanted. This will affect whether the fluidadheres to the surface. Thus, to improve performance of a device, it maybe desirable to identify regions where fluids pass, or are likely to getclogged. These identified regions can then be ion implanted to affecttheir hydrophobicity, reducing risk of clogging and improve deviceperformance.

FIG. 10 shows a representative biochip. The biochip 800 may be used forsingle nucleotide polymorphism (SNP) detection in DNA. The biochip 800includes a variety of different functions, which are physicallyseparated in the device 800. For example, fluids may enter the device800 via an entrance 801. This fluid may pass through a meander mixerwith obstacles 802. After sufficient mixing, the fluid enters a thermalchamber 803. After being heated, the fluid enters a filter section,including a coarse filter 804 and a fast and selective micropillarfilter 805. These sections are each created by processing a suitableworkpiece 807. After the workpiece 807 is processed, it is covered, suchas by a glass plate 806.

These different functions within the device 800 may have differingrequirements. For example, to enhance the mixing ability, it may bebeneficial to affect the properties of the material in the meandermixer, but not in other areas. Furthermore, enhanced mixing may occur ifthe hydrophobicity within different regions of the meander mixer differ.A focused or patterned ion implant to selectively affect thehydrophobicity (or hydrophilicity) of various portions of the materialin the meander mixer may enhance mixing. Similarly, the micropillarfilter 805 may benefit from increasing hydrophobicity. Since themicropillars are very small features with high aspect ratio, conformallycoating each of them, as is currently done, is ineffective. A conformalion implant, using the apparatus of FIG. 2, may affect the materialproperties without increasing the size of the individual micropillars.This ion implant enables a better control of the conformal treatment andthe adhesion of the treatment to the micropillar with minimal increaseof micropillar size. In addition, it may be advantageous to not affectthe properties of other parts of the biochip 800. For example, thethermal chamber 803 may not be treated at all. Of course, othervariations are also possible. This only serves to illustrate the abilityto selectively affect a material's properties on a very small scale toimprove device performance. In addition, it would be advantageous ifthese treatments do not affect the bonding of the workpiece 807 to theglass cover 806. These precise treatments of the regions may beimportant in this respect.

FIG. 11 shows another example of a MEMs device 850. This device is amicropump, and includes a number of individual workpieces 851 a-d whichall affixed to each other after processing to form the pump 850. Thelower workpiece 851 a includes an inlet area 852, an outlet area 853 andan outlet membrane, or flap 854. The first intermediate workpiece 851 bincludes an inlet membrane or flap 855, an inlet area 856, and an outletarea 857. The second intermediate workpiece 851 c has a movablediaphragm 858. The top workpiece 851 d has a counter electrode 859. Inoperation, the diaphragm 858 moves upward, creating a partial vacuum inthe chamber 860. This causes liquid to push the inlet membrane 855upward, allowing fluid to pass through the inlet areas 852, 856 and intothe chamber 860. When the diaphragm 858 moves downward, it forces thefluid in the chamber 860 to push the outlet flap 854 downward, allowingthe fluid to exit the outlet areas 857, 853. For proper operation, itmay be beneficial to affect those parts of the device which are movable,such as the material that comprises the inlet membrane 855 and theoutlet flap 854. It may be beneficial to insure that these portions donot adhere to the other portions of the workpieces 851 a-d. This mayinvolve changing the adhesion properties or hydrophobicity of themembranes 854, 855, or the portions of the workpieces that contact thesemembranes 854, 855. It may also be beneficial to treat the diaphragm 858to insure that it does not adhere to the counter electrode 859.Alternatively, the counter electrode 859 may be treated. In someembodiments, treatments for the micropump are focused only on a portionof the workpiece so that other portions are not treated at all, or mayreceive a different treatment.

As described above, the implant will reduce or prevent adhesion by afluid. The ion species that is implanted may in part affect thehydrophobicity. Certain energy levels or doses during implantation maymodify the lattice structure of the surfaces, which also may in partaffect the hydrophobicity. Other mechanisms due to implant that affectthe hydrophobicity may be possible. The implanted regions will remainhydrophobic even if cleaned because the implanted regions are part ofthe surface instead of a coating on the surface that may be eroded orwashed off. To maintain the hydrophobic state, at least a few monolayersof the surface may be implanted. Uniformity of the dose and depthimplanted regions may be controlled.

MEMS and NEMS devices can include any micro or nano mechanical device.This includes accelerometers, gyroscopes, sensors, micro-actuators (suchas micro-pumps, micro-flaps, micro-valves, optical switches, ormirrors), thermalactuators, micromirrors, micro-resonators,piezoelectric detectors, cantilevers, microbalances, pressure sensors,bio-MEMS, biosensors, chemosensory, microphones, electrostatic motors,microfluidics devices, interferometric modulator displays, picoprojectors, RF MEMS antennas, RF filters, RF MEMS phase shifters, orother devices. Other localized blanket or patterned implants, etching,or deposition steps also can be performed on a MEMS or NEMS device.Electrical, optical, or magnetic properties also can be affected bythese implants or treatments. Focused multi-angle processing can beperformed on a 2D or 3D device. In some instance, localized regions downto approximately 5 μm feature size can be treated.

While much of this disclosure describes implanting ions into a surface,the disclosure is not limited to this embodiment. For example, theapparatus of FIG. 2 may be used to add coatings or layers to an existingfeature or structure. FIG. 5 is a cross-sectional side view of sidewallporous material formation. Certain MEMS and NEMS devices requiresidewall porous material formation, but the small dimensions makedeposition difficult. For example, silicon, porous silicon, diamond-likecarbon, or other materials may be formed on a sidewall. Ions 102 areused to form a layer 401 on the sidewalls of the feature 400. The layer401 may be between 5 nm to 100 nm thick, for instance. This can beperformed by adjusting the angles of the ions 102. In some instances,forming a layer on the base of the feature 400 or only on one sidewallof the feature 400 is possible. Different thicknesses of the layer 401are possible on different surfaces by adjusting the angle spread of theions 102 or the relative doses within the angle spread of the ions 102.

This porous material formation may occur on many types of device. Forexample in one embodiment, the sidewalls of an accelerometer 900 aretreated to add porous material, as shown in FIG. 12. Capacitance, orsensitivity, of an accelerometer is proportional to surface area.Increased surface area of the accelerometer sidewall can make it moresensitive to movements. Since porous materials have a much largersurface area than planar surfaces, this can significantly increase thesensitivity of the device 900. In some embodiments, one or both of theSOI fixed parts 901 and the SOI moving parts 902 are treated to addporous material on their sidewalls.

Porous material deposition can be used to form a protective layer arounda device. In one embodiment, devices intended for placement in the bodymay be coated using the apparatus of FIG. 2 to make them biocompatible.Devices can also be coating to change other properties, such ashydrophobicity.

In yet other embodiments, it may be beneficial to use ion implantationto affect the material's resistance to various chemicals. In oneembodiment, the treatment disclosed herein uses a low energy implant,which is faster and less complex than a high energy implant. Theseembodiments also only may affect the first 0 to 100 nm of a material,though other depths are possible. By only affecting a small layer of theimplanted material, less of the overall material will have itsproperties changed and the flexibility of the material is not negativelyimpacted. Thus, the properties at the surface of the material may beaffected without affecting the entire workpiece. This may beadvantageous, in that it is possible to change the chemical resistanceof some materials or devices without affecting their flexibility.

FIG. 6 is a cross-sectional side view of workpiece being implanted. Theworkpiece 501 may be composed of, for example, polymer, glass, plastic,insulators, metals, or other materials. While the workpiece 501 may havea 2D or planar surface 504 as illustrated in FIG. 6, this implant alsocan apply to 3D structures. With such a 3D structure, a multi-angleimplant can treat all surfaces of the 3D structure. Also, while theentire surface 504 is illustrated as being treated with the ions 500, aselective or patterned implant may be performed. A selective implantwill scan the surface 504 with respect to the ions 500 and adjust thebias to the surface 504 (or workpiece 501 containing the surface 504) orplasma conditions such that only a portion of the surface 504 isimplanted.

The ions 500 form an implant region 502 that penetrates the surface 504of the workpiece 501. The depth of the implant region 502 (i.e.dimension 503) may be between approximately 0 to 100 nm, for example.The implant profile can be Gaussian or a surface peak to accommodatedifferent chemical resistance properties. The ions 500 may be, forexample, a noble gas or other inert species, though other species arepossible. In one instance, the ions 500 are Ar, Ne, Kr, Xe or He andthese ions break some of the bonds on the surface 504 and in the implantregion 502 that make this surface 504 sensitive to certain chemicals.Thus, the workpiece 501 has its surface properties altered.Cross-linking of the surface 504 also may be affected by the low energyimplantation. For example, lactone or ester groups of a polymer can bedestroyed using such a low energy plasma treatment. In yet anotherembodiment, an active species is used for the implant, such as N₂, H₂,NF₃ C_(x)H_(y), C_(x)F_(y), SiF₄, SiH₄, disilane or CF₄. This activespecies can be implanted to cause a chemical change in the surface 504.This may be used instead of or to supplement the physical changes causedby the implant.

FIG. 13 is a cross-sectional side view of one embodiment of a 3D feature1400 being implanted. The incidence angles of the ions 102 are used suchthat implant regions 1401 are formed only on the sidewalls of the 3Dstructure 1400. Of course, only the base of the 3D structure 1400 may beimplanted in an alternate embodiment. In yet another embodiment, thesidewalls and base of the 3D structure 1400 are implanted to differentdepths or with different doses. This can be accomplished, for example,by adjusting the angle spread of the ions 102 or relative doses of ions102 within the angle spread. Other 3D structures are possible andselective implant can be performed on only some surfaces while othersurfaces are not treated. In some cases, only one side of the featureneeds to be implanted. An example of this may be MEMS sensors.

In one particular embodiment, a sealing layer is placed on a surfaceusing a helium (He) implant. This implant with He reduces sputtering anddamage to the areas below the implant region. In one instance, this canbe used with polymers. This sealing layer may be between 1 nm and 30 nmin one instance and may break some bonds of the surface to change thelocal composition.

Experiments have shown that implanting He into a polymer layer canaffect chemical resistance. In the experiment, the polymer was notresistant to acetone prior to the implant but was resistant to acetoneafter the implant. FIGS. 7A-B represents an embodiment of Heimplantation into a structure. In FIG. 7A, the polymer, in this casephotoresist, is patterned. In this embodiment, the photoresistpatterning comprises a series of vertical walls 700. In FIG. 7B, thephotoresist is then implanted with helium to harden the polymer. FIG. 8Ashows the patterned photoresist. Vertical walls of various thicknessesare created on the workpiece. FIG. 8B shows a workpiece, which did notundergo the process of FIG. 7B, after a 5 second acetone rinse. Withouttreatment, the polymer was removed from the sample in acetone. FIG. 8Cshows a workpiece, which underwent the process of FIG. 7B. With a Heimplant, the polymer remained intact after an acetone treatment. Thus,the pattern shown in FIG. 8C is the same as that of the unrinsedreference sample, shown in FIG. 8A. This He implant can be combined withCF₄ to make the resulting polymer hydrophobic as well.

The ability to affect chemical resistance has other importantapplications as well. For example, for industrial printing technology,such as solar metal contact printing, printed electronics, flexibleelectronics and other application, there is a need for solvent basedink. Because of this, the material used in the printer heads needs to bealso compatible with these aggressive liquids. Traditional polymer basedcavity and channel may not be compatible. Thus, by introducing an ionimplantation, as described above, the hydrophobicity requirement may bemaintained while increasing the resistance to chemicals, such as theseinks.

In some embodiments, ultraviolet (UV) light can be used to improve thechemical resistance. Plasma often generates light at variousfrequencies. Therefore, the light and UV emitted from the plasmaadditionally can affect chemical resistance by breaking some of thebonds in the polymer. The frequency of the light may be tunable by usingdifferent extraction plate materials. In some embodiments, theextraction plate acts as a light filter, when different materials willhave different transparencies. Thus, selection of an appropriatematerial for the extraction plate may change the frequencies which thepolymer is exposed to. Therefore, if the materials that surround theplasma or are disposed between the plasma and the implanted workpiececan be selected to transmit certain types of UV light, this energy cansupplement the implanted ions.

One advantage of some of the embodiments described herein is thatfeature dimensions of the structure or surface may the same after theimplant. Unlike other treatments, one or more layers are not added tothe surface. Instead, the surface itself is affected. A second advantageis that the ions can smooth a surface using certain implant parameters.This may or may not affect the dimensions of the surface. The scale ofthe smoothing can vary with the implant parameters.

Print heads, microfluidics, MEMS devices, NEMS devices or biomedicalapplications may need chemical resistance when designed to transportliquid from one region to another. This liquid may be an industrialchemical, water, a bodily fluid, or other material. These devices may be3D structures with high aspect ratios. A third advantage is that theembodiments described herein can enable the dimensions to remain small(or totally unaffected) while providing total or patterned chemicalresistance.

Although reference is made to MEMS devices, NEMS devices and inkjetprinter heads, other devices also can benefit. For example, organiclight-emitting diodes (OLEDs) can be treated between each organic layer.During production of OLEDS, a first organic layer is deposited by spincoating and then baked. A second organic layer is then deposited. Thesolvent from the second organic layer may attack the first organiclayer. Therefore, implantation of the first organic layer to render itmore chemical resistant can improve OLEDs. Other devices that transportor carry liquids or have interfaces between organic layers can alsobenefit.

In addition, other materials, such as gloves, boots, fabric, protectiveclothing, or protective equipment, can be rendered more resistant tochemicals such as, for example, acid. Inkjet printer cartridges, heads,or nozzles can be rendered more resistant to certain inks or chemicals.Other devices or materials also can be implanted to affect chemicalresistance.

The present disclosure is not to be limited in scope by the specificembodiments described herein. Indeed, other various embodiments of andmodifications to the present disclosure, in addition to those describedherein, will be apparent to those of ordinary skill in the art from theforegoing description and accompanying drawings. Thus, such otherembodiments and modifications are intended to fall within the scope ofthe present disclosure. Furthermore, although the present disclosure hasbeen described herein in the context of a particular implementation in aparticular environment for a particular purpose, those of ordinary skillin the art will recognize that its usefulness is not limited thereto andthat the present disclosure may be beneficially implemented in anynumber of environments for any number of purposes. Accordingly, theclaims set forth below should be construed in view of the full breadthand spirit of the present disclosure as described herein.

What is claimed is:
 1. A method of affecting a workpiece's chemicalresistance, comprising: performing a low energy implant of a speciesinto part of a surface of a workpiece, wherein the species comprises anoble gas.
 2. The method of claim 1, wherein the surface comprises a 3Dfeature.
 3. The method of claim 2, where the part of the surfacecomprises a sidewall of the 3D feature.
 4. The method of claim 1,wherein the workpiece comprises a material selected from the groupconsisting of polymer, glass, plastic, insulators and metal.
 5. Themethod of claim 1, wherein a depth of the low energy implant is between1 and 100 nm.
 6. The method of claim 1, wherein bonds on the surface ofthe workpiece are broken by the low energy implant of the species. 7.The method of claim 1, wherein the low energy implant of the speciescreates an implant region in the workpiece, and bonds in the implantregion are broken by the low energy implant of the species.
 8. Themethod of claim 1, wherein the low energy implant has a Gaussian implantprofile.
 9. The method of claim 1, wherein the low energy implant has asurface peak implant profile.
 10. The method of claim 1, wherein theworkpiece comprises a polymer; and lactone or ester groups of thepolymer are destroyed by the low energy implant of the species.
 11. Themethod of claim 1, wherein the species comprises helium and a sealinglayer is created on the surface of the workpiece by the low energyimplant.
 12. The method of claim 11, wherein the workpiece comprises apolymer.